Lockout mechanisms for surgical instruments

ABSTRACT

Surgical instruments include a first drive assembly having a first drive gear and a lockout mechanism positioned for releasable engagement with the first drive assembly to inhibit rotation of the first drive gear. The lockout mechanism includes a pawl and an actuator for moving the pawl from a first position in engagement with the first drive gear to a second position spaced from the first drive gear.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of and priority to U.S. Provisional Patent Application Ser. No. 62/779,187 filed Dec. 13, 2018, the entire disclosure of which is incorporated by reference herein.

BACKGROUND Technical Field

The present disclosure relates to surgical instruments. More particularly, the present disclosure relates to lockout mechanisms for surgical instruments.

Background of Related Art

Surgical instruments for, e.g., applying staples, clips, or other fasteners to tissue, are well known. Generally, surgical instruments include an actuation unit, e.g., a handle assembly for actuating the instrument, an elongate shaft for accessing a body cavity, and a tool assembly disposed at a distal end of the elongate shaft. The surgical instruments may be manual or powered. Typically, one or more drive assemblies extend from the handle assembly, through the elongate shaft of the surgical instrument for effecting at least one function of the end effector, e.g., clamping, stapling, or cutting.

It would be beneficial to have a surgical instrument with one or more mechanical lockout mechanisms to inhibit operation of the surgical instrument prior to certain conditions being met and/or to prevent a second or subsequent operation of the surgical instrument.

SUMMARY

According to an aspect of the present disclosure, a surgical instrument is provided. The surgical instrument includes a first drive assembly including a first drive gear; and a lockout mechanism positioned for releasable engagement with the first drive assembly to inhibit rotation of the first drive gear. The lockout mechanism includes a pawl and an actuator means for moving the pawl from a first position in engagement with the first drive gear to a second position spaced from the first drive gear.

In embodiments, the pawl includes a plurality of teeth and the first drive gear includes a plurality of teeth. The plurality of teeth of the pawl may engage the plurality of teeth of the first drive gear when the pawl is in the first position. The pawl may pivot from the first position to the second position. The surgical instrument may further include an adapter assembly. The first drive assembly and the lockout mechanism may be disposed within the adapter assembly. The actuator may include a motor, a servo, or an electromagnet.

The surgical instrument may further include a handle assembly. The adapter assembly may be releasably secured to the handle assembly. In addition, the surgical instrument may further include an end effector releasably secured to the adapter assembly. The end effector may include a loading unit and an anvil assembly.

Also provided is a surgical instrument including an elongate body, a drive member received within the elongate body, a trocar assembly releasably receivable within the elongate body, and a retaining mechanism for releasably securing the trocar assembly within the elongate body. The drive member includes a flange and is movable between a retracted position and an advanced position. The trocar assembly includes a trocar housing defining first and second opposed openings. The retaining mechanism includes a cam wire including a free end and is moveable between a locked position and an unlocked position. When the cam wire is in the locked position, the free end of the cam wire obstructs a path of the flange of the drive member to inhibit movement of the drive member to the advanced position.

In embodiments, the retaining mechanism further includes first and second retaining members moveably positioned about the cam wire. The first and second retaining members may be releasably receivable within the first and second opposed openings of the trocar housing when the trocar assembly is seated within the elongate body. The cam wire may be in the unlocked position when the first and second retaining members are received within the first and second opposed openings in the trocar housing. The cam wire may be in the locked position when the first and second retaining members engage the trocar housing.

The retaining mechanism of the surgical instrument may further include a release button for moving the cam wire between the unlocked position and the locked position. The retaining mechanism may further include a retaining block through which the trocar assembly is received. The free end of the cam wire may extend from the retaining block when the cam wire is in the locked position. The free end of the cam wire may be disposed within the retaining block when the cam wire is in the unlocked position.

In addition, a surgical instrument is provided that includes a drive member including a cutout defined by a distal facing surface, and a lockout mechanism disposed adjacent to the drive member. The lockout mechanism includes a locking member pivotally secured relative to the drive member and moveable from a first position in engagement with the distal facing surface of the drive member and a second position spaced from the distal facing surface of the drive member, the drive member being moveable from the first position to the second position by an electromagnet.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and, together with a general description of the disclosure given above, and the detailed description of the embodiments given below, serve to explain the principles of the disclosure, wherein:

FIG. 1 is a perspective view of a surgical stapling instrument including a handle assembly, an adapter assembly, and an end effector;

FIG. 2 is a perspective view of the surgical stapling instrument shown in FIG. 1, with the adapter assembly separated from the handle assembly;

FIG. 3 is a perspective view of a proximal portion of the adapter assembly shown in FIG. 1, including a rotation knob assembly;

FIG. 4 is a perspective view of the rotation knob assembly shown in FIG. 3, with a housing half of the rotation knob assembly removed;

FIG. 5 is a cross-sectional end view taken along line 5-5 shown in FIG. 3, with a lockout mechanism in a locked condition;

FIG. 6 is a cross-sectional end view taken along line 5-5 shown in FIG. 3, with the lockout mechanism in an unlocked condition;

FIG. 7 is a perspective side view of an adapter assembly including a removable trocar;

FIG. 8 is a perspective side view of a retaining mechanism and a lockout mechanism of the adapter assembly shown in FIG. 7, with the lockout mechanism in a locked position;

FIG. 9 is a cross-sectional end view taken along line 9-9 shown in FIG. 7, with the lockout mechanism shown in FIG. 8;

FIG. 10 is a perspective view of a drive member of the adapter assembly shown in FIG. 7;

FIG. 11 is a perspective view of the wire cam, retaining members, and a release button of the lockout mechanism shown in FIG. 8;

FIG. 12 is a perspective side view of the retaining mechanism and the lockout mechanism shown in FIG. 7, with the lockout mechanism in an unlocked position;

FIG. 13 is a cross-sectional end view taken along line 13-13 shown in FIG. 12, with the lockout mechanism shown in FIG. 8;

FIG. 14 is a partial cross-sectional side view of a lockout mechanism according to another embodiment of the present disclosure, with a plunger member in a locked position;

FIG. 15 is a partial cross-sectional side view of the lockout mechanism shown in FIG. 14, with the plunger member in an unlocked position;

FIG. 16 is a partial cross-sectional side view of a drive member of the lockout mechanism shown in FIGS. 14 and 15;

FIG. 17 is a partial cross-sectional side view of a lockout mechanism according to another embodiment of the present disclosure, with a plunger member in a locked position;

FIG. 18 is a partial cross-sectional side view of the lockout mechanism shown in FIG. 18, with the plunger member in an unlocked position;

FIG. 19 is a partial cross-sectional side view of a lockout mechanism according to another embodiment of the present disclosure, with a plunger member in a locked position; and

FIG. 20 is a partial cross-sectional side view of the lockout mechanism shown in FIG. 19, with the plunger member in an unlocked position.

DETAILED DESCRIPTION

Embodiments of the presently disclosed lockout mechanisms will now be described in detail with reference to the drawings in which like reference numerals designate identical or corresponding elements in each of the several views. As is common in the art, the term “proximal” refers to that part or component closer to the user or operator, e.g. surgeon or clinician, while the term “distal” refers to that part or component farther away from the user.

Referring initially to FIGS. 1 and 2, an adapter assembly including a lockout mechanism according to an embodiment of the present disclosure, shown generally as adapter assembly 100, is a component of a surgical stapling instrument 10. The surgical stapling instrument 10 further includes a powered handle assembly 20, and an end effector 30. As shown, the end effector 30 includes a loading unit 40, and an anvil assembly 50. Although shown and described with reference to surgical stapling instrument 10, the aspects of the present disclosure may be modified for use with surgical instruments having one or more drive assemblies for effecting actuation of an end effector. For a detailed description of exemplary powered surgical stapling instruments, please refer to commonly owned U.S. Pat. Nos. 9,023,014 and 9,055,943 (“the '014 patent” and “the '943 patent”, respectively), the contents of each of which are incorporated by reference herein in their entirety.

The adapter assembly 100 of the surgical stapling instrument 10 will only be described to the extent necessary to fully disclose the aspects of the present disclosure. For a detailed description of exemplary adapter assemblies, please refer to commonly owned U.S. Pat. App. Pub. Nos. 2015/0157321 (“the '321 publication), 2016/0106406 (“the '406 publication”), and 2017/0086879 (“the '879 publication”), the contents of each of which are incorporated by reference herein in their entirety.

With continued reference to FIGS. 1 and 2, the adapter assembly 100 includes a proximal portion 102 configured for operable connection to the handle assembly 20 (FIG. 1) and a distal portion 104 configured for operable connection to the loading unit 30 (FIG. 1). Although shown and described as forming an integral unit, it is envisioned that the proximal and distal portions 102, 104 may be formed as separate units that are releasably securable to one another.

With reference to FIGS. 3 and 4, the proximal portion 102 of the adapter assembly 100 includes a rotation knob assembly 110. The rotation knob assembly 110 includes a base 112, and a rotation knob 114 rotatably secured to the base 112. The base 112 is configured to operably connect the adapter assembly 100 with the handle assembly 20.

With particular reference to FIG. 4, a drive coupling assembly 120 is operably disposed within the base 112 of the rotation knob assembly 110. The drive coupling assembly 120 engages first, second and third drive shafts (not shown) of the handle assembly 20 (FIG. 1). A drive transfer assembly 130 is disposed within the rotation knob 114 of the rotation knob assembly 110 and is operably secured to the drive coupling assembly 120. The drive coupling assembly 120 and drive transfer assembly 130 remain rotationally fixed relative to the handle assembly to which adapter assembly 100 is attached, e.g., handle assembly 20.

The drive coupling assembly 120 and the drive transfer assembly 130 together form first, second, and third drive assemblies 140, 145, 150. The first, second, and third drive assemblies 140, 145, 150 may each effect a different operation of an attached end effector, e.g., end effector 30 (FIG. 1). For example, the first drive assembly 140 may effect tissue stapling, the second drive assembly 145 may effect tissue cutting, and the third drive assembly 150 may effect tissue clamping.

With particular reference to FIG. 5, in one embodiment of the present disclosure, a lockout mechanism 160 includes a pawl 162 operably disposed within the rotation knob assembly 110 of the adapter assembly 100. The pawl 162 is pivotally supported relative to a first drive gear 152 of the third drive assembly 150. The pawl 162 includes a plurality of teeth 164 a on a free end 164. The plurality of teeth 164 a is configured to engage the first drive gear 152 of the third drive assembly 150. In embodiments, and as shown, the plurality of teeth 164 a of the pawl 162 is configured to inhibit rotation of the first drive gear 152 in a first direction, e.g., clockwise, and permit rotation of the first drive gear 152 in a second direction, e.g., counter-clockwise. In this manner, the lockout mechanism 160 may permit retraction of the third drive assembly 150 while preventing advancement of the third drive assembly 150. Alternatively, the plurality of teeth 164 a of the pawl 162 may be configured to inhibit rotation of the first drive gear 152 in both the first and second directions.

Although shown and described with the pawl 162 in engagement with the first drive gear 152 of the third drive assembly 150, it is envisioned that the lockout mechanism 160 may be modified to include one or more pawls that engage any of the gears of any combination of the first, second, and third drive assemblies 140, 145, 150.

Turning to FIG. 6, when the handle assembly 20 (FIG. 1) of the surgical stapling instrument 10 is programmed to detect if certain parameters are satisfied, e.g., proper loading of a trocar assembly 170 within the adapter assembly 100, and when satisfied, the handle assembly 20 activates the lockout mechanism 160 to disengage the pawl 162 from the first drive gear 152 of the third drive assembly 150 to permit rotation of the first drive gear 152. In embodiments, the lockout mechanism 160 includes an actuator 166, e.g., a motor, servo, electromagnet or other suitable means for pivoting the pawl 162 out of engagement with the first drive gear 152. Once the pawl 162 disengages from the first drive gear 152, the third drive assembly 150 operates in a traditional manner.

The handle assembly 20 may be programmed to reengage the pawl 162 of the lockout mechanism 160 with the first drive gear 152 of the third drive assembly 150 subsequent to firing of the surgical stapling instrument 10 to prevent reuse of the surgical stapling instrument 10. Similarly, the and/or at any time during the stapling procedure when locking of the third drive assembly 150 may become desired, e.g., malfunction of the surgical stapling instrument 10 (FIG. 1).

With reference now to FIG. 7, a lockout mechanism according to another embodiment of the present disclosure will be shown and described with reference to an adapter assembly 200, and a removable trocar assembly 210 releasably disposable within a distal portion 204 of the adapter assembly 200. The adapter assembly 200 is substantially similar to adapter assembly 100 described hereinabove, and will only be described in detail as relates to the differences therebetween.

The trocar assembly 210 includes a housing 212 and a trocar member 214 selectively extendable from the housing 212. The housing 212 defines a pair of openings 213 (FIG. 13). As will be described in further detail below, the housing 212 of the trocar assembly 210 is configured to be engaged by a retaining mechanism 240 when the trocar assembly 210 is fully received and seated within the distal portion 204 of the adapter assembly 200 to secure the trocar assembly 210 within the adapter assembly 200.

With reference now to FIGS. 8 and 9, the retaining mechanism 240 of the adapter assembly 200 is disposed between first and second drive members 222, 224, 232, 234 of respective first and second drive assemblies 220, 230. The first and second drive assemblies 220, 230 are operably connected to first and second drive members (not shown) in a proximal portion 202 of the adapter assembly 200 for effecting operation of an end effector, e.g., the end effector 30 (FIG. 1), to perform first and second functions. More particularly, the first and second drive members 222, 224, 232, 234 of the respective first and second drive assemblies 220, 230 are configured for longitudinal movement within the distal portion 204 of the adapter assembly 200. In embodiments, advancement of the first drive assembly 220 effects tissue stapling, and advancement of the second drive assembly 230 effects tissue cutting.

The first and second drive assemblies 220, 230 will only be described to the extent necessary to fully disclose the aspects of the present disclosure. For a detailed description of exemplary drive assemblies, please refer to the '879 publication, the content of which was previously incorporated herein.

With additional reference to FIG. 10, the first drive member 222 of the first drive assembly 220 includes an elongate band 222 a and a flange portion 222 b extending outwardly from a proximal portion of the elongate band 222 a. As will be described in further detail below, the flange portion 222 b of the first drive member 222 is configured to be engaged by a wire cam or spring clip 244 of a lockout mechanism 250 to inhibit advancement of the first drive assembly 220 when the trocar assembly 210 is not fully received and seated within the adapter assembly 200.

With continued reference to FIGS. 8 and 9, and additional reference to FIG. 11, the retaining mechanism 240 of the adapter assembly 200 includes a retaining block 242, a wire cam 244 (FIG. 9), a pair of retaining members 246 (FIG. 9), and a release button 248 (FIG. 11). The retaining block 242 of the retaining mechanism 240 defines a central opening 241 for receiving the trocar assembly 210, a pair of opposed cylindrical openings 241 a in communication with the central opening 241 for receiving the retainer members 246, and a channel or slot 241 b extending about a perimeter of the retaining block 242 and through the cylindrical openings 241 a in the retaining block 242 for receiving the wire cam 244. The retainer members 246 of the retaining mechanism 240 are supported within the cylindrical openings 241 a by the wire cam 244 and are configured to be received within the openings 213 (FIG. 9) in the housing 212 of the trocar assembly 210 when the trocar assembly 210 is fully received and seated within the distal portion 204 of the adapter assembly 200.

The wire cam 244 of the retaining mechanism 240 includes a substantially U-shaped body 244 a having a pair of opposed angled sections 244 b and free ends 244 c. The wire cam 244 is received within the channel 241 b of the retaining block 242 and is moveable between a first position (FIG. 9) when the trocar assembly 210 is partially received within the distal portion 204 of the adapter assembly 200, e.g., the retaining members 246 are not aligned with the openings 213 in the housing 212 of the trocar assembly 200, and a second position (FIG. 13) when the trocar assembly 210 is fully received within the distal portion 204 of the adapter assembly 200, e.g., the retaining members 246 are aligned with and received in the openings 213 in the housing 212.

With particular reference to FIGS. 8 and 9, when the wire cam 244 of the retaining mechanism 240 is in the first position, the free ends 244 c of the wire cam 244 extend beyond the retainer block 242 of the retaining mechanism 240. The first drive member 222 of the first drive assembly 220 and the retaining block 242 of the retaining assembly 240 are configured such that one of the free ends 244 c of the wire cam 244 of the retainer assembly 240 engages the flange 222 b of the first drive member 222 to form the lockout mechanism 250. The lockout mechanism 250 inhibits operation of the first drive assembly 220, e.g., advancement of the first drive member 222. Although shown with only one of the free ends 244 c of the wire cam 244 engaging the first drive member 222 of the first drive assembly 220, it is envisioned that the first drive member 222 may be configured to engage both free ends 244 c of the wire cam 244. In embodiments, the engagement of the first drive member 222 of the first drive assembly 220 with the flange 222 b of the first drive member 222 provides sufficient resistance to movement that the handle assembly 20 (FIG. 1) detects and identifies that the trocar assembly 210 is not fully received and properly seated within the adapter assembly 200.

The retaining members 246 of the retaining mechanism 240 are supported on the angled portions 244 b of the wire cam 244. The retaining members 246 may include an inclined inner surface 246 a (FIG. 11) to facilitate receipt of the trocar assembly 210 therebetween. The retaining members 246 each define an opening 245 through which the respective angled section 244 b of the wire cam 244 is received. The wire cam 244 and the retaining members 246 are configured such that when the trocar assembly 210 is not fully received within the distal portion 204 of the adapter assembly 200, the wire cam 244 is maintained in the first position (FIG. 9), with the free ends 244 c of the wire cam 244 extending beyond the retaining block 242. In this manner, at least one of the free ends 244 c of the wire cam 244 engages the first drive member 222 of the first drive assembly 220 to inhibit advancement of the first drive member 222.

As shown in FIGS. 8 and 9, when the trocar assembly 210 is received within the distal portion 204 of the adapter assembly 200 and when the openings 213 in the housing 212 of the adapter assembly 200 are not aligned with the retaining members 246, the housing 212 of the trocar assembly 210 biases the retaining members 246 outward, as indicated by arrows “A” in FIG. 9. The angled sections 244 c of the wire cam 244 and the openings 245 in the retaining members 246 are configured such that when the retaining members 246 are biased outwardly through contact with the housing 212 of the trocar assembly 210, the cam wire 244 is biased upwardly, as indicated by arrows “B” in FIG. 9, to cause the free ends 244 c of the cam wire 244 to extend beyond the retaining block 242 and into the path of the first drive member 222 of the first drive assembly 220.

With reference to FIGS. 12 and 13, when the trocar assembly 210 is fully received and properly seated within the distal portion 204 of the adapter assembly 200 (FIG. 13), e.g., the openings 213 of the housing 212 of the trocar assembly 210 are aligned with the retaining members 246 of the retaining mechanism 240, the retaining members 246 move within the openings 213 in the housing 212 of the trocar assembly 210, as indicated by arrows “C” in FIG. 13. Movement of the retaining members 246 into the openings 213 of the housing 212 moves the cam wire 244 downwardly (as illustrated in FIG. 9) such that the free ends 244 c of the cam wire 244 are retracted within the retaining block 242. Retraction of the free ends 244 c of the cam wire 244 within the retaining block 242 clears a path for the first drive member 222 of the first drive assembly 220. The adapter assembly 200 then operates in a traditional manner.

Following a stapling procedure with adapter assembly 200, the trocar assembly 210 may be released from the adapter assembly 200 by pressing the retaining button 248 of the retaining mechanism 240 to cause the cam wire 244 to move upwardly (as illustrated in FIG. 9) and result in the retaining members 246 moving outwardly from within the openings 213 in the housing 212 of the trocar assembly 210. Once the retaining members 246 clear the openings 213 in the housing 212, the trocar assembly 210 may be removed from within the distal portion 204 of the adapter assembly 200.

With reference now to FIGS. 14-16, another lockout mechanism according to the present disclosure is shown generally as lockout mechanism 300. As shown, the lockout mechanism 300 is configured to inhibit advancement of a drive member 312 of a drive assembly 310. More particularly, the lockout mechanism 300 includes a locking member 302 that is pivotally secured relative to the drive member 312. The locking member 302 is configured to be received within a cutout 313 in the first drive member 312. The cutout 313 is defined by a vertical distal facing surface 314 a and a sloped proximal facing surface 314 b. When the locking member 302 is received within the cutout 313 and in engagement with the vertical distal facing surface 314 a, the locking member 302 inhibits movement of the drive member 312.

The lockout mechanism 300 further includes an electromagnet 304 disposed adjacent the locking member 302. When activated, the electromagnet 304 causes the locking member 302 to pivot out of the cutout 313 in the drive member 312, thereby permitting advancement of the drive member 312. Although shown as including an electromagnet 304, it is envisioned that the locking member 302 may be moved with a motor, solenoid, or other mechanism. Although shown as being pivoted out of engagement with the drive member 312, it is envisioned that the locking member 302 may instead by retracted or otherwise moved in a linear manner from within the cutout 313.

With particular reference to FIG. 16, a distance “x” between the vertical distal facing surface 314 a of the drive member 312 and the sloped proximal facing surface 314 b of the drive member 312 determines the distance the drive member 312 may be advanced before the lockout mechanism 300 engages. The greater the distance “x”, the greater the distance the drive member 312 may be advanced prior to the lockout mechanism 300 engaging.

Turning to FIGS. 17 and 18, another lockout mechanism according to the present disclosure is shown generally as lockout mechanism 400. The lockout mechanism 400 includes a housing 410, a plunger member 420, a biasing member, e.g., spring 430, and an electromagnet 440. Although shown including a housing 410, it is envisioned that the lockout mechanism 400 may be incorporated directly into an adapter assembly, e.g., adapter assembly 100.

The housing 410 of the locking mechanism 400 includes a cylindrical recess 411, a cutout 413, and a passage 415 extending between the cylindrical recess 411 and the cutout 413. The plunger member 420 includes a head portion 422 and an elongate body portion 424. The head portion 422 is received within the cylindrical recess 411 and the elongate body portion 424 extends through the passage 415 into the cutout 413. The biasing member, e.g., spring 430, is disposed within the cylindrical recess 411 and biases the plunger member 420 in a first direction, as indicated by arrow “F” in FIG. 17, into an extended or locked position. In the locked position, the elongate body portion 424 of the plunger member 420 extends from the passage 415 into the cutout 413.

The electromagnet 440 is disposed adjacent the cylindrical recess 411 opposite the passage 415. Activation of the electromagnet 440 retracts the plunger member 420 against the bias of the spring 430, as indicated by arrow “G” in FIG. 18, into a retracted or unlocked position. When the plunger member 420 is in the unlocked position, the elongate body portion 424 of the plunger member 420 is retracted from within the cutout 413 of the housing 410 of the locking mechanism 400 such that the cutout is unobstructed.

In operation, the locking mechanism 400 is positioned within a surgical instrument, e.g., surgical stapling instrument 10 (FIG. 1), such that the cutout 413 of the housing 410 is in alignment with a path (not shown) of a drive member (not shown) or connecting element 450. When the plunger member 420 is in the locked position, the elongate body portion 424 of the plunger member 420 is disposed within the cutout 413, thereby obstructing the path of the drive member and/or connector member 450 and preventing advancement of the drive member through the housing 410 of the locking mechanism 400 and/or connection of the connector member 450 with the housing 410.

As noted above, activation of the electromagnet 440 causes the plunger member 420 to retract to the unlocked position (FIG. 18), thereby clearing the path through the cutout 413 in the housing 410. In this manner, the drive member (not shown) is able to pass through the housing 410 unobstructed. Similarly, the connector member 450 is able to be received within the cutout 413 in the housing 410 of the locking mechanism 400 to secure the connector member 450 with the housing 410.

With reference now to FIGS. 19 and 20, a locking mechanism according to another embodiment of the present disclosure is shown generally as locking mechanism 500. The locking mechanism 500 is substantially similar to locking mechanism 400 described hereinabove, and will only be described in detail as relates to the difference therebetween.

In the locking mechanism 500, a plunger member 520 is maintained in a retracted or unlocked position (FIG. 20) within a cylindrical recess 511 of a housing 510 by a biasing member, e.g., spring 530, as indicated by arrow “G” in FIG. 20. When in the unlocked position, an elongate body portion 524 of the plunger member 520 obstructs a cutout 513 in the housing 510 to prevent advancement of a drive member (not shown) and/or preventing receipt of a connector member 550 within the cutout 513.

The locking mechanism 500 includes a pneumatic valve 540 in communication with the cylindrical recess 511. Activation of the pneumatic valve 540 pressurizes the cylindrical recess 511 thereby causing the plunger member 520 to move to an advanced or locked position (FIG. 19) within the cylindrical recess 511, as indicated by arrow “I” in FIG. 19, against the bias of the spring 530. When the in the locked position. The elongate body portion 524 of the plunger member 520 is received within the cutout 513 of the housing 510, thereby obstructing the path of the drive member and/or connection member 550.

Persons skilled in the art will understand that the devices and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments. It is envisioned that the elements and features illustrated or described in connection with one exemplary embodiment may be combined with the elements and features of another without departing from the scope of the present disclosure. As well, one skilled in the art will appreciate further features and advantages of the disclosure based on the above-described embodiments. Accordingly, the disclosure is not to be limited by what has been particularly shown and described. 

The invention claimed is:
 1. A surgical instrument comprising: an elongate body; a drive member received within the elongate body, the drive member including a flange and being movable between a retracted position and an advanced position; a trocar assembly releasably receivable within the elongate body, the trocar assembly including a trocar housing defining first and second opposed openings; and a retaining mechanism for releasably securing the trocar assembly within the elongate body, the retaining mechanism including a cam wire including a free end, the cam wire being moveable between a locked position and an unlocked position, wherein when the cam wire is in the locked position, the free end obstructs a path of the flange of the drive member to inhibit movement of the drive member to the advanced position.
 2. The surgical instrument of claim 1, wherein the retaining mechanism further includes first and second retaining members moveably positioned about the cam wire, the first and second retaining members being releasably receivable within the first and second opposed openings of the trocar housing when the trocar assembly is seated within the elongate body.
 3. The surgical instrument of claim 2, wherein the cam wire is in the unlocked position when the first and second retaining members are received within the first and second opposed openings in the trocar housing.
 4. The surgical instrument of claim 2, wherein the cam wire is in the locked position when the first and second retaining members engage the trocar housing.
 5. The surgical instrument of claim 2, wherein the retaining mechanism further includes a retaining block through which the trocar assembly is received.
 6. The surgical instrument of claim 5, wherein the free end of the cam wire extends from the retaining block when the cam wire is in the locked position.
 7. The surgical instrument of claim 6, wherein the free end of the cam wire is disposed within the retaining block when the cam wire is in the unlocked position.
 8. The surgical instrument of claim 1, wherein the retaining mechanism further includes a release button for moving the cam wire between the unlocked position and the locked position.
 9. A surgical instrument comprising: an elongate body; a drive member received within the elongate body, the drive member being movable between a retracted position and an advanced position; and a retaining mechanism for releasably securing a trocar assembly within the elongate body, the retaining mechanism including a cam wire moveable between a locked position and an unlocked position, wherein when the cam wire is in the locked position, the cam wire obstructs a path of the drive member to inhibit movement of the drive member to the advanced position.
 10. The surgical instrument of claim 9, wherein the drive member includes a flange and the cam wire includes a free end.
 11. The surgical instrument of claim 10, wherein the free end of the cam wire obstructs a path of the flange of the drive member to inhibit movement of the drive member.
 12. The surgical instrument of claim 10, further including a trocar assembly releasably receivable within the elongate body, the trocar assembly including a trocar housing defining first and second opposed openings.
 13. The surgical instrument of claim 12, wherein the retaining mechanism further includes first and second retaining members moveably positioned about the cam wire, the first and second retaining members being releasably receivable within the first and second opposed openings of the trocar housing when the trocar assembly is seated within the elongate body.
 14. The surgical instrument of claim 13, wherein the cam wire is in the unlocked position when the first and second retaining members are received within the first and second opposed openings in the trocar housing.
 15. The surgical instrument of claim 13, wherein the cam wire is in the locked position when the first and second retaining members engage the trocar housing.
 16. The surgical instrument of claim 12, wherein the retaining mechanism further includes a retaining block through which the trocar assembly is received.
 17. The surgical instrument of claim 16, wherein the free end of the cam wire extends from the retaining block when the cam wire is in the locked position.
 18. The surgical instrument of claim 17, wherein the free end of the cam wire is disposed within the retaining block when the cam wire is in the unlocked position.
 19. The surgical instrument of claim 9, wherein the retaining mechanism further includes a release button for moving the cam wire between the unlocked position and the locked position.
 20. A surgical instrument comprising: a handle assembly; an elongate body releasably secured to the handle assembly; a drive member received within the elongate body, the drive member including a flange and being movable between a retracted position and an advanced position; a trocar assembly releasably receivable within the elongate body, the trocar assembly including a trocar housing defining first and second opposed openings; and a retaining mechanism for releasably securing the trocar assembly within the elongate body, the retaining mechanism including a cam wire including a free end, the cam wire being moveable between a locked position and an unlocked position, wherein when the cam wire is in the locked position, the free end obstructs a path of the flange of the drive member to inhibit movement of the drive member to the advanced position. 